1. Field of the Invention
The invention relates to technology of a grasping apparatus capable of reliably grasping any of a plurality of types of workpieces of different shapes.
2. Description of Related Art
When handling a plurality of types of workpieces of different shapes with a grasping apparatus that grasps a workpiece or a product or the like, it is troublesome to replace a contact portion, i.e., a portion of the grasping apparatus that directly contacts the workpiece or the like, with a portion corresponding to the shape of each workpiece. Therefore, it has been hoped that a grasping apparatus capable of flexibly handling a variety of types of workpieces having different outer shapes would be developed. So, various technologies for grasping apparatuses that are capable of successfully grasping a variety of types of workpieces having different outer shapes have been examined. Japanese Patent Application Publication No. 9-123082 (JP-A-9-123082), for example, described below describes just such a technology.
JP-A-9-123082 describes a grasping apparatus provided with a contact portion capable of handling various outer shapes by encapsulating a large amount of granular substance inside a flexible membrane, and reducing the pressure in the membrane using a vacuum pump or the like, or canceling that pressure reduction. With this grasping apparatus, a contact portion is arranged at a tip end of a support device such as a robotic arm or the like. Also, with a grasping operation by the robotic arm or the like, the contact portion is made to abut against the workpiece or the like and conform to the shape of the workpiece or the like. Then the large amount of granular substance inside the membrane is held tightly and the shape of the contact portion is kept conformed to the shape of the workpiece. Also, with this grasping apparatus, the contact portion is returned to its normal shape by canceling the reduced pressure state in the contact portion. Also, using such a related grasping apparatus enables the shape of the contact portion to match the outer shapes of various workpieces and the like. As a result, when handling a plurality of various workpieces having different outer shapes, the workpieces can be stably grasped.
If the contact portion is displaced (becomes offset) with respect to the robotic arm or the like, the positioning accuracy is unable to be ensured. Therefore, the contact portion of the related art is typically firmly fixed by a method such as adhesion so that it will not be displaced with respect to the robotic arm or the like. As a result, however, it is not easy to replace the contact portion if it becomes damaged from abrasion or cutting or the like. Therefore, it is difficult to apply a grasping apparatus having a contact portion like that of the related art to a workpiece that has multiple edge portions or to a workpiece to which cutting dust is adhered.